Troubleshooting Tandem Connection Issues with VPNs (like Mullvad)
If you’ve recently experienced dropped calls, "reconnecting" loops, or a total failure to join a meeting in Tandem, the culprit might not be your Wi-Fi, it might be your VPN.
We’ve identified a specific technical conflict between Tandem’s connection protocol and certain VPN clients, specifically Mullvad, when they are installed on desktop machines and not necessarily in use. Here is a breakdown of what’s happening and how to fix it.
The Technical "Why"
Tandem relies on WebRTC (Web Real-Time Communication) to power high-quality video and audio. To make sure your call is as fast as possible, WebRTC uses a process called ICE (Interactive Connectivity Establishment) negotiation.
During this phase, Tandem:
- Scans your machine for every available network interface.
- Gathers "candidates" (potential connection paths).
- Probes them with STUN/TURN requests to find the most efficient route to your teammates.
The Problem: "Phantom" Tunnels
When certain VPNs—like Mullvad—are installed, they sometimes enter a "half-state." Even if you have clicked "Disconnect," the VPN may leave behind multiple active tunnel interfaces.
Because these tunnels are still "up" but aren't actually routing traffic anywhere, Tandem’s connection process gets stuck. It spends valuable time trying to verify these "dead" tunnels, which leads to:
- Long connection times
- Broken audio/video
- Frequent "reconnecting" messages
The Solution
If you are seeing these issues and have a VPN installed, we recommend the following steps:
- Fully Quit/Disable the VPN: Ensure no background processes are running.
- The Clean Test: If the issue persists, try uninstalling the VPN temporarily and restarting Tandem.
- Report Back: If removing the VPN solves your connection issues, please reach out to our support team.
Note on Mullvad: We have actively investigated Mullvad and confirmed that these phantom interfaces are a primary cause of failure. We are currently in contact with their team to find a more permanent compatibility fix.
We want your Tandem experience to be seamless. If you're still hitting walls after trying the above, let us know so we can dig deeper into your specific setup!